Freezing point lowering agents are in widespread use for a variety of purposes, especially to reduce the freezing point of an aqueous system so that ice cannot be formed or to melt formed ice. Generally, freezing point lowering agents depend for their effectiveness upon the molar freezing point lowering effect, the number of species which are made available and the degree to which the agent can be dispersed in the liquid phase in which the formation of ice is to be precluded and/or ice is to be melted.
A common use for freeze point lowering agents is in road deicers. Traditionally, deicers comprising a solid salt, such as sodium chloride rock salt, were spread onto roadways (solid deicers); however, there is a growing trend to use liquid deicers for improved deicer performance. In fact, aqueous solutions of salts (liquid deicers) are more effective at preventing ice formation than solid salt because the solution can be applied more evenly on the road and is not displaced by vehicle traffic, thus resulting in a more efficient use of the salt.
The most pervasive of the commonly used products for deicing are common salt, calcium chloride, magnesium chloride, acetates and urea, with common salt (sodium chloride) being the least expensive and most commonly used. Common salt is widely used to melt ice on road surfaces and the like. In this manner, the salt forms a solution with the available liquid in contact with the ice and thereby forms a solution with a lower freezing point than the ice itself so that the ice is melted. Chloride salts, while inexpensive, suffer from relatively severe drawbacks, such as the harmful effects on surrounding vegetation by preventing water absorption in the root systems, and its corrosive effects on roadway infrastructure and motor vehicles. A downside to the use of liquid salt deicers is increased corrosion problems arising from the use of salt water. To mitigate the corrosive effects corrosion inhibitors are added to the salt solution (See, for example, U.S. Pat. No. 7,658,861).
Typically, liquid deicers comprise two components which originate from two different sources, namely, (1) a brine; and (2) a corrosion inhibitor containing solution (which is typically supplied in the form of a concentrated solution). The brine and corrosion inhibitor containing solution are stored separately until combined in the field when needed at the time of use. One of the key requirements for corrosion inhibiting containing solutions is that these solutions be stable in cold storage. Specifically, the corrosion inhibiting containing solution cannot freeze above a certain temperature or form any insoluble material. Therefore, freeze point lowering agents must be added to the corrosion inhibitor solutions to mitigate ice formation. Commonly the freeze point agents are the same salts that constitute the deicing solution, namely sodium chloride or magnesium chloride. However, the addition of freeze point lowering agents to the corrosion inhibitor solutions causes problems. Specifically, these agents tend to form insoluble salts with the corrosion inhibitor or promote crystallization of the corrosion inhibitor through the common ion effect. Therefore, there is a need in the art for new corrosion inhibiting, freeze point lowering agents that when stored in cold temperatures, sufficiently lower the freeze point while forming minimal to no solids.